(a) Field of the Invention
This invention relates to an improvement in or relating to the configuration of a ski so as to provide skis which are readily turnable by not only advanced skiers but also beginners and those having weak leg strength.
(b) Description of the Prior Art
As apparent from FIG. 1 which illustrates in plan a conventional ski, the prior art ski has a front ski half extending between the front ground line 2, which is in contact with a horizontal plane 10 in a front part of the ski, and the middle part 4; a rear ski half extending from the middle part 4 to the rear ground line 3 lying in the horizontal plane 10 in a rear part of the ski; a gliding surface 9; and a boot-binding part 7 located substantially at the same point as the middle part 4 and adapted to permit a skier to mount his foot thereon upon using the ski. More specifically, the ski is, as seen in plan, broadest at the ski shoulder in the vicinity of the front ground line, narrowest at the ski waist around the middle part along the length of the ski, and has a width approximately intermediate of the widths at the former two locations at the ski heel near the rear ground line 3. The right and left contours 5, 6 define at each side of the ski an inwardly-indented gentle curve between the front ground line 2 and rear ground line 3, which curve has a radius of about 50-55 m or so. As readily seen from FIG. 2, which is a side elevation of the above conventional ski, the gliding surface 9 of the ski lies in the horizontal plane 10 at two points, i.e., at the front ground line 2 and rear ground line 3. Its middle part 7 is defined by an arch-like curve havin a weight bottom camber 11 of about 3.0-18.00 mm. Thus, the gliding surface 9 is upwardly spaced from the horizontal plane 10, in other words, the chord joining the front ground line 2 and rear ground line 3 when the ski is unoccupied.
Skis of the above-mentioned type, however, require a high degree of complex technique such as body weaving, weight exertion and release at the weight bottom camber 11, stepping-in, and timing when making a turn thereon. Such prior art skis are accompanied by another drawback that, due to the formation of the weight bottom camber 11 at the boot-binding part 4, great leg strength is required to enable each of them to touch the snow along its length. This is because of the repulsive force developed by the springiness stemming from the lengthwise arched structure of the ski. Strain, tension, etc. are even when a skier's weight is exerted thereon, thereby making ski-handling difficult for those lacking such great leg strength.
To change the skiing direction upon making a turn on such conventional skis, it is necessary, as envisaged from FIG. 9, which illustrates in plan positions of the conventional skis, in the course of making a turn, to push upwardly and draw the rear portion of the ski strip, i.e., the outer side contour 6 of the rear ski half 13 in the vicinity of the rear ground line 3, while using the front ground line 2 as the center of the turning motion. This forces the skier to uncomfortably shift his heels from each other, thereby casting an extra, undue burden to his waist, knees and arms so as to maintain balance. With such prior art skis, it is also necessary for a skier to intentionally push the ski tails outwardly whenever he tries to make a turn. This renders it difficult for the skier to maintain balance because his gravity center tends to shift from the ski strips in the course of each turning motion. To cope with this inconvenience, the skier is required to glide down over the snow while making uncomfortable waist, knee and arm positions.
In the early stage of each turning motion (i.e., introductory stage), it is also necessary with conventional skis to make a turn using complex body motion in which the skier is required to repeatedly exert and release his body weight relative to the skis by bending and stretching his legs. In the later stage of each turning motion, conventional skis require a high degree of skiing technique including undue edging and excessive rocking to avoid oversliding of the ski tails, notably on the packed snow, on frozen ski slopes and the like. As a result, such conventional skis draw considerably serpentine zigzag lines as shown in FIG. 11 which illustrates the tracks left in the snow when a skier glided downhill, thereby forcing the skier to expend more energy.